The use of optical fiber as a transmission medium is growing at an accelerating rate. The advantages of optical fibers over other forms of transmission media are well known. The potential bandwidth (or message carrying capacity) of optical fibers is extremely high. Systems using optical fibers are resistant to electromagnetic interference which sometimes plagues systems having electrical cables. In addition, optical fiber cabling offers a higher degree of data security than such electrical cables, as it is more difficult for unauthorized personnel to tap or access an optical fiber cable without being detected.
Optical fiber devices use single or multiple strands of fibers each having an inner circular glass core coated with a circumferential cladding having a different index of refraction. Light is transmitted along the core and totally reflected from the interface between the core and cladding. Such devices can be used as transmission lines for transmitting information bearing light energy. A transmission line can be formed from a single fiber or it can include a plurality of fibers bundled together as a cable. Additionally, several transmission lines can be arranged in parallel for the simultaneous transmission of information along each of the separate lines.
Where the transmission line is relatively long and extends between different pieces of apparatus, the transmission line is divided into segments and the different segments are connected to each other using separable optical fiber connectors which have been developed to meet this need. Typically, such connectors are positioned within a common housing (or adapter) in opposing relationship. The principle design criteria of such connectors is to connect the transmission lines in an end-to-end relationship in such a manner as to minimize the loss of light energy as light traverses from one end of one line into the end of the adjacent segment of that line. Such minimal loss between the connected fibers is essential when the optical fibers, which typically terminate in ferrules located in a connector body, are aligned coaxially and when the fiber faces, each of which is typically planar, contact in a common plane. Optical fiber connectors must be designed to bring the ends of the transmission lines into as perfect an axial alignment as possible in order to assure such minimal loss. Considering the size of the fibers (e.g., one with a core diameter of about 10 microns and a cladding diameter of 100 to 150 microns), the task of alignment is, understandably, a challenging one.
When a transmission line is comprised of a plurality of individual fibers joined together to form a bundle or cable, for the transmission of a single piece of information along the line, the alignment of each individual fiber, one to another, is not critical, as any light energy escaping from one fiber would be accepted into the fibers on the other side. However, where a transmission line is made up of a single individual fiber, it is extremely critical that perfect alignment take place, as any escaping light energy may be lost.
There presently exist various connector assemblies in the art which are capable of attaining end-to-end alignment, once the selected individual optical fiber connectors (each having at least one optical fiber and ferrule located in a suitable body (or housing)) are positioned within a designated common housing or adapter. Due to manufacturing tolerances, however, proper alignment between these individual connectors and common housing is often difficult, particularly when attempting to align and position paired arrangements of such individual connectors. To accomplish this, individual optical fiber and ferrule subassemblies have been encased within a singular housing, often referred to in the art as a duplex connector, and then inserted within the corresponding, common housing. Separation of these individual connectors (typically two) in such a substantially fixed arrangement is, obviously, difficult. Because of this relatively rigid form of encasement, flexibility of movement between the ends of these individual components is substantial prohibited, thus complicating final alignment and positioning of the connectors within the designated common housing.
As will be defined herein, the instant invention provides what can also be referred to as a duplex connector, but one wherein originally separate, individual optical fiber connectors (including fiber, ferrule and a suitable body, or housing) are retained in not only a side-by-side orientation capable of being inserted within a corresponding common housing( to form a connector assembly) but also an orientation which permits freedom of movement between said individual connectors so as to accomodate for manufacturing tolerances in the common housing and/or housings of the individual connectors, thereby facilitating such alignment. Additionally, the duplex connector as defined herein meets current standards for keying variations, using easily changed covers which snap securely into place.
It will be understood from the teachings herein that the duplex connector assembly of the invention is adapted for being precisely oriented within an adapter such as mentioned above (e.g., wherein a matching pair of connectors in another common housing are positioned in the adapter's opposite end for alignment with the invention's paired connectors), or, alternatively, within a common housing (also occasionally referred to as a shroud) such as the one defined in U.S. Pat. No. 5,005,939, which patent is incorporated herein by reference. Concerning the latter, the defined motion (a/k/a "float") of the invention accommodates for manufacturing tolerances in the receiving portions (a/k/a "bores") of such a common housing. Understandably, such "float" also facilitates positioning and alignment within a common adapter such as defined above. One example of an adapter for receiving at least one duplex connector is shown in U.S. Pat. No. 4,687,291, and referred to as an interconnect member. This interconnect member may also receive a pair of single connectors within an opposing end thereof. It is understood that the invention is also adapted for being positioned within such an interconnector, to thereby couple with an associated pair of singular connectors located therein.
It is believed that such an assembly would constitute a significant advancement in the art.